I'm wondering, does anybody know of similar things for other languages. Complete offline documentation that you can use if you don't have wireless for a while.

For C#, Visual Studio gives you the option to download and install the entire online documentation as a part of the VS2008 install, so if you have Visual Studio 2008, then you have the C# offline documentation.

EDIT: if you're gonna say this and that is possible, please post hyperlinks.

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Python also has downloadable documentation. As a result, most operating systems which provide Python also provides a documentation package. For instance, on Debian, this is package python2.5-doc (one package per version).

Install it and you can browse the documentation offline. Very convenient for a laptop which is not always connected.

Scroll down the page and look for the link called Java SE 6 Documentation. It is a series of HTML files covering the entire Java SE JDK. It can be handy to have it stored locally, but because there is no search functionality, its uses are somewhat limited.